Amino acid composition of droughtmaster beef at various beef cuts

doi:10.4236/as.2013.45B012

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Vol.4, No.5B, 61-64 (2013) Agricultural Sciences

doi:10.4236/as.2013.45B012

Amino acid composition of droughtmaster beef at

various beef cuts

Zainal Samicho, Siti Roha Ab Mutalib*, Noriham Abdullah

Department of Food Technology, Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Malaysia;

*Corresponding Author: siti_roha23@yahoo.com.my

Received 2013

ABSTRACT

A total of 14 parts of beef cuts were used to de-

termine the amino acid composition in drought-

master beef. Drought-master beef is a cross

breed tropical cattle with 50% Shorthorn and

50% Brahman cattle. The most abundant type of

amino acid in drought-master beef was glutamic

acid, followed by aspartic acid, lysine, leucine

and arginine. The flank cut of beef was found to

contain higher amount of total amino acids fol-

lowed by top side and short rib cut of beef. The

amino acid composition of drought-master beef

indicates that beef is a good source of dietary

protein for human.

Keywords: Amino Acid; Droughtmaster Beef; Beef

Cut and Acid hydrolysis

1. INTRODUCTION

Beef has an excellent nutritional quality because it has

proteins of high biological value, it is rich in vitamin

contents, especially B-complex, and it is associated to a

high mineral content, especially iron, in high bioavail-

ability form [1]. Beef contains all the amino acids in

about the right proportions required by humans [2].

Many studies deal with the opportunities of enhancing

the beneficial fatty acids (increasing the n-3 polyunsatu-

rated fatty acids and conjugated linoleic acids (CLA) and

reducing saturated fatty acids (SFA)) in beef, but little is

known about the alteration of other nutritional ingredi-

ents (amino acid composition and mineral content) in

beef [3,4].

Meat and meat products are good sources of protein

for human consumption. These proteins are well bal-

anced in amino acid and contain all essential amino acid

that human cannot be synthesized. However, because of

health effect some people cannot consumed meat. Ac-

cording to [5], several essential amino acids such as leu-

cine and phenylalanine and non essential amino acid

such as arginine and glutamine, have shown to directly

stimulate insulin secretion from pancreatic beta-cells, so

as it has beneficial therapeutic effect in patient with type

2 diabetes.

Droughtmaster beef is mixed tropical cattle 50%

Shorthorn and 50% Brahman cattle. It can stand with hot

and humid conditions resist to tick and good reproduc-

tion. Up to date, there is no amino acid study on beef

species droughtmaster have been done and there are few

studies focused on amino acid in different beef cut.

Therefore, the aim of the experiments was to establish

different amino acid content in different droughtmaster

beef cut.

2. MATERIAL AND METHODS

Amino acid kit (AccQ Tag) was purchased from Wa-

ters. All other chemicals were purchased from Sigma.

Beef were purchased from Rantau Panjang, Selangor,

Malaysia.

2.1. Preparation of Beef

14 parts of beef cut were used in this study. The parts

are neck clod, short rib, shin, flank, rump, brisket, thick

flank, top side, silver side, thin rib, thick rib, chuck blade,

sirloin and leg.

2.2. Acid Hydrolysis

The amino acid composition of the samples was ana-

lyzed by digesting the samples for 24 hour at 110℃ in

an oven with 5 ml of 6 N HCl in sealed glass test tubes.

The aliquot of the hydrolysate was taken and 0.4 ml

AABA (alpha amino butyric acid (50 μmol ml-1)) was

added to it as the internal standard. Then 100 ml of de-

ionized water was added to the aliquot. This aliquot was

then filtered using whatman filter paper No.1 followed

by a syringe filter.

2.3. Derivatization of Amino Acids with

6-aminoquinolyl-N-hydroxysuccinimidy

l Carbamate (AQC)

A cleaned syringe was used to deliver 10 μL filtrate of

Z. Samicho et al. / Agricultural Sciences 4 (2013) 61-64

acid hydrolysis to the bottom of a cleaned 6 × 50 mm

sample tube. A 70 μL of AccQ•Fluor Borate Buffer (Re-

agent 1) was then added to the sample tube by using a

micropipette. The sample tube was vortexed briefly prior

to adding of 20 μL of reconstituted AccQ•Fluor Reagent

to the sample tube. After vortexed for several seconds,

the sample tube was let to stand for 1 minute at room

temperature.

2.4. Preparation of Internal Standard and

Calibration Standard

The internal standard, AABA stock solution was used

to prepare the calibration standard. To prepare a 50

μmol/mL internal standard stock solution, 0.258 g AABA

was added to 50 mL 0.1N HCl. Prior to the preparation

of the calibration standard with an internal standard, 1

mL of 50 μmol/mL internal standard stock solution was

transferred to a cleaned 20 mL volumetric flask. The

solution was then made up to 20 mL with 0.1 N HCl until

the final concentration of the internal standard solution

was 2.5 μmol/mL. The calibration standard consisted of

1:1 (v/v) mixture of Pierce H amino acid standard (which

contained 2.5 μmol/mL of each amino acid standard,

except for 1.25 μmol/mL of cystine) and a 2.5 μmol/mL

of AABA. Typically, a calibration standard with an in-

ternal standard was prepared by combined 80 μL 2.5

μmol/mL AABA with 80 μL Pierce H and then was made

up with 840 μL deionized water in a 1000 μL cleaned

vial. A volume of 10 μL calibration standard (contains of

2 nmol of each standard amino acid components) was

transferred from the 1:1 (v/v) mixture of Pierce H amino

acid standard, and 2.5 μmol/mL of AABA was placed in

a derivatisation tube and carried through the same deri-

vatisation procedure as mentioned earlier.

2.5. HPLC Analysis of Amino Acids

The Waters AccQ•Tag amino acid analysis method

requires a fluorescence detector. The excitation wave-

length was 285 nm, the emission wavelength was 354

nm, filter and gain set were 1.5 second and 10, respec-

tively. Eluent A and Eluent B were AccQ•Tag concen-

trate and 60% acetonitrile: water, respectively. The col-

umn temperature was set at 37℃. The Column (Waters

AccQ•Tag) was first conditioned with Eluent B at 1

mL/min flow rate for 5 minutes. This was followed by

equilibrating the column in 100% AccQ•Tag Eluent A for

9 minutes at the same flow rate. Consistent period of the

equilibration was kept for all the analysis. A blank was

carried out before each analysis to determine baseline

performance. The gradient shown in Table 1 was used in

the process of analyzing amino acids using HPLC. The

total time between injections to end of the analysis was

50 minutes.

Table 1. Gradient table for amino acids analysis using HPLC.

Time (mi n)Flow rate (mL/min) %A %B

Initial 1.0 100.0 0.0

0.50 1.0 98.0 2.0

15.0 1.0 90.0 10.0

19.0 1.0 87.0 13.0

32.0 1.0 65.0 35.0

33.0 1.0 65.0 35.0

34.0 1.0 0.0 100.0

37.0 1.0 0.0 100.0

38.0 1.0 100.0 0.0

50.0 1.0 100.0 0.0

2.6. Statistical Analysis

All data were expressed as mean ± standard deviation.

Data were analysed using one-way ANOVA using SPSS

15.0. Duncan’s multiple-range test was used to determine

the difference between means. A significant difference

was considered at the level of p < 0.05.

3. RESULTS AND DISCUSSION

Droughtmaster beef was used in this study and it was

divided into 14 parts of beef cut. The method used in this

study only allowed analysis of 17 amino acids. These

amino acids were arginine, lysine, valine, threonine, leu-

cine, tyrosine, histidine, isoleucine, phenylalanine, me-

thionine, cysteine, glycine, proline, alanine, glutamic

acid, aspartic acid and serine. Upon acid hydrolysis, as-

paragines and glutamine could be hydrolyzed to aspartic

acid and glutamic acid, respectively. Thus, the content of

aspartic acid represents the total content of asparagines

and aspartic acid, and the same applies to glutamic acid.

Tryptophan is destroyed upon acid hydrolysis, thus was

not measured in this study.

Table 2 shows the amino acids content in different

beef cuts. The amino acid content is presented as gram

amino acid/ 100 gram total amino acids. The major

components of amino acid were glutamic acid, followed

by aspartic acid, lysine, leucine and arginine. There was

significant difference at the 5% level in the amino acid

contents among 14 parts of beef cuts tested.

The content of aspartic acid, serine, glutamic acid, ar-

ginine, threonine, valine, methionine, lysine, isoleucine,

leucine and phenylalanine was significantly higher in

flank cut of beef part. This finding was in agreement

with studied done by [6] on the amino acid content in

fresh and cooked beef cuts. Furthermore, the content of

certain amino acid such as tyrosine, alanine and histidine

were significantly higher in top side of beef cut. On the

other hand, proline and glycine was significantly higher

in short rib and cysteine was higher in thick flank of beef

cut.

Z. Samicho et al. / Agricultural Sciences 4 (2013) 61-64

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Z. Samicho et al. / Agricultural Sciences 4 (2013) 61-64

In summary there is no general pattern correlation

between the beef cut and amino acid content in beef.

When comparing between different parts of beef cut, the

amino acid content in beef cut were almost similar. The

most abundant amino acid in beef (in decreasing order)

was glutamic acid, aspartic acid, lysine, leucine, cysteine,

arginine, glycine and phenylalanine. However, histidine

and methionine were present in much lower amount

which was in agreement with [6]. The essential amino

acid comprised more than 40% of total amino acid con-

tent of beef cut. The total amino acid content for neck

clod, short rib, shin, flank, rump, brisket, thick flank, top

side, silver side, thin rib, thick rib, chuck blade, sirloin

and leg were 16.36, 20.50, 14.31, 28.02, 19.95, 19.71,

14.94, 23.70, 15.68, 14.26, 10.33, 14.71, 12.00 and 10.49

(g/100 g of sample) respectively.

When comparing this research finding with previous

studied done by [6], there is slightly different in the

amount of amino acid content. The rationale for this may

be due to different species of beef, animal age, effect of

feeding high or low amino acid compound, processing

[7], slaughter weight and gender [8].

With regards the uses of amino acid, several essential

amino acids such as leucine and phenylalanine and non

essential amino acid such as arginine and glutamine,

have shown to directly stimulate insulin secretion from

pancreatic beta-cells, so as it has beneficial therapeutic

effect in patient with type 2 diabetes [5] and [9]. Ac-

cording to [10], 1 mmol/kg lean body mass leucine plus

25 g glucose will synergistically stimulate insulin secre-

tion. Another function of leucine is to stimulate protein

synthesis, inhibit protein degradation and nutrient sig-

naling molecule [10]. Amino acids are also important in

healing process. Deficiency in essential amino acids may

hinder healing recovery process [11]. Leucine promotes

the healing of bones, skin and muscle tissue. Isoleucine

is necessary for haemoglobin formation, stabilizing and

regulating blood sugar and energy. Glycine, which is one

of the major components of human skin collagen, to-

gether with other essential amino acids such as alanine

form a polypeptide that will promote regrowth and tissue

healing [12].

4. CONCLUSIONS

The amino acid composition of beef cut showed that it

is a good source of dietary amino acid. With regard to its

nutritional value, beef provides all the essential amino

acids needed by human. The essential amino acid cannot

be manufactured by human bodies but can be obtained

from food. Flank cut of beef is found rich in leucine

which is type of essential amino acid that can stimulate

insulin secretion.

5. ACKNOWLEDGEMENTS

Special thanks to Ministry of Higher Education, Malaysia for fund-

ing this project under Fundamental Research Grant Scheme [600-RMI/

ST/FRGS/Fst(32/2010)].

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